JPH0743679A - Automatic adjusting device for liquid crystal display density - Google Patents

Abstract

PURPOSE:To automatically adjust display density according to the change in a voltage and an ambient temperature. CONSTITUTION:An adjustment table is stored in a ROM 13. By an LCD driving circuit 12, a driving voltage based on a density setting value stored in an internal memory is supplied to an LCD 11. By a voltage detection circuit 16, the driving voltage from the LCD driving circuit 12 is detected, and the voltage data are outputted. By a temperature sensing circuit 17, the ambient temperature is sensed, and the temperature data are outputted. By a CPU 15, the change value of the driving voltage is obtained based on the voltage data from the voltage detection circuit 16, and on the other hand, the change value of the ambient temperature is obtained based on the temperature data from the temperature sensing circuit 17, and the adjustment table in the ROM 13 is consulted based on both change values, and a density adjustment value is obtained, and the new density setting value is obtained. Then, the density setting value of the LCD driving circuit 12 is updated by the new density setting value. In such a manner, the liquid crystal display density is revised optimally and automatically according to the changes of the driving voltage and the ambient temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display density automatic adjustment device capable of automatically adjusting the liquid crystal display density in a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, there is a liquid crystal display density adjusting device for adjusting a liquid crystal display density in a liquid crystal display device as shown in FIG.

This liquid crystal display density adjusting device comprises a liquid crystal display (LCD) 1, an LCD drive circuit 2, a ROM (read
It is roughly composed of an only memory) 3, a density adjustment key 4 and a CPU (central processing unit) 5.

The optimum liquid crystal display density value at the battery initial voltage at room temperature (25 ° C.) is stored in the ROM 3 as an initial value of liquid crystal display density (hereinafter, simply referred to as density initial value). Then, the CPU 5 first sends the density initial value read from the ROM 3 to the LCD drive circuit 2 as a liquid crystal display density setting value (hereinafter, simply referred to as density setting value). Then, the LCD drive circuit 2 drives the LCD 1 with a drive voltage based on the density set value, and an image is displayed on the LCD 1 at a liquid crystal display density according to the density set value.

In this way, the quality of the image density displayed on the LCD 1 is judged by the operator. As a result, when it is determined that the liquid crystal display density needs to be changed due to the change in the liquid crystal display density due to the change in the battery voltage, the operator operates the density adjustment key 4.
Then, the CPU 5 adjusts the liquid crystal display density by the density adjustment key 4 with respect to the initial density value.
A value obtained by adding (hereinafter, simply referred to as a density adjustment value) is sent to the LCD drive circuit 2 as a new density set value. And
The LCD driving circuit 2 drives the LCD 1 based on the new density setting value, and an image is displayed on the LCD 1 with the liquid crystal display density corrected according to the new density setting value.

Further, as a contrast adjusting device for a liquid crystal display section different from the above, the following one has been proposed (Japanese Patent Laid-Open No. 63-161487).

In this liquid crystal contrast adjusting device, the optimum bias value according to the ambient temperature of the liquid crystal display section is stored in the storage section. Then, the control unit reads the optimum bias value corresponding to the ambient temperature detected by the temperature detection unit from the storage unit, and controls the contrast of the liquid crystal display unit by the read optimum bias value.

[0008]

However, the above-mentioned conventional liquid crystal display density adjusting device has the following problems.

In the liquid crystal display density adjusting device in which the initial density value at the battery initial voltage at room temperature (25 ° C.) is adjusted by the density adjustment key, the optimum liquid crystal display at the battery initial voltage at room temperature (25 ° C.) is used as described above. The density value is used as the initial density value. By the way, a display device using a battery as an LCD display power source is generally installed in a portable information device.
Therefore, for example, when a portable information device set to the optimum liquid crystal display density in a room at room temperature is used outdoors at 0 ° C., the density initial value itself changes and
The liquid crystal display density of CD1 will change. Therefore, the operator needs to adjust the liquid crystal display density according to the change in the ambient temperature in addition to the original adjustment of the liquid crystal display density according to the change in the battery voltage, which causes a problem of extra operation.

In the liquid crystal contrast adjusting device disclosed in Japanese Patent Laid-Open No. 63-161487, the liquid crystal display density can be adjusted according to the change of the environmental temperature, but the liquid crystal display density is adjusted according to the change of the power supply voltage. Is impossible. However, since the liquid crystal display contrast greatly depends on the change in the power supply voltage, it must be able to cope with the change in the power supply voltage.

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic liquid crystal display density adjusting device capable of automatically adjusting the liquid crystal display density according to changes in power supply voltage and environmental temperature.

[0012]

In order to achieve the above object, an automatic liquid crystal display density adjusting device of the present invention supplies a driving voltage based on a liquid crystal display density set value stored in an internal memory to a liquid crystal display. A liquid crystal display drive unit, a voltage detection unit that detects a drive voltage from the liquid crystal display drive unit and outputs a voltage information signal that represents the drive voltage, and a temperature information signal that senses the environmental temperature and represents the sensed temperature. A temperature sensing unit that outputs a driving voltage change amount, an environmental temperature change amount, and an adjustment table storage unit that stores an adjustment table that associates the liquid crystal display density adjustment value corresponding to the change amount, and the voltage detection unit. The change amount of the driving voltage and the change amount of the ambient temperature are calculated based on the voltage information signal from the temperature sensor and the temperature information signal from the temperature sensor. The liquid crystal display density adjustment value is calculated based on the table, and the liquid crystal display density adjustment value stored in the internal memory of the display drive section is updated based on the calculated liquid crystal display density adjustment value. It is characterized by having.

[0013]

The liquid crystal display drive unit supplies the liquid crystal display with a drive voltage based on the liquid crystal display density set value stored in the internal memory. At the same time,
The drive voltage is detected by the voltage detection unit and a voltage information signal representing the drive voltage is output. Also, the temperature sensing unit senses the environmental temperature and outputs a temperature information signal indicating the sensed temperature.

Then, the liquid crystal display density adjusting unit calculates the drive voltage change amount and the environmental temperature change amount based on the voltage information signal from the voltage detection unit and the temperature information signal from the temperature detection unit, and this calculation is performed. The liquid crystal display density adjustment value is obtained using the adjustment table stored in the adjustment table storage unit based on the two change amounts. Further, based on the obtained liquid crystal display density adjustment value, the liquid crystal display density set value stored in the internal memory of the display drive section is updated.

In this way, when the driving voltage and the ambient temperature change, the liquid crystal display density set value is automatically changed according to the changes, so that the liquid crystal display density in the liquid crystal display is always kept optimal. .

[0016]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a block diagram of the liquid crystal display density automatic adjustment apparatus of this embodiment.

This automatic liquid crystal display density adjusting device is equipped with an LC
In addition to the D11, the LCD drive circuit 12, the ROM 13, the density adjustment key 14 and the CPU 15, the voltage detection circuit 16 and the temperature detection circuit 17 are roughly configured.

The LCD 11 includes an LCD driver,
An image is displayed on the pixel matrix based on the drive voltage signal supplied from the LCD drive circuit 12. The LCD drive circuit 12 is composed of, for example, an LVC that produces a four-valued drive voltage, and at the time of start-up, it generates the drive voltage signal based on the density set value stored in the internal memory, and LC
Supply to D11. The drive voltage signal from the LCD drive circuit 12 is also supplied to the voltage detection circuit 16. Then, the voltage detection circuit 16 sets the voltage of the drive voltage signal to A
The digital value representing the drive voltage obtained by the / D conversion is stored in the internal memory, and the obtained digital drive voltage of the LCD 11 and the digital signal representing the previous drive voltage stored in the internal memory (hereinafter referred to as voltage). C)
It is sent to PU11.

The temperature sensing circuit 17 has a temperature sensing unit such as a thermistor, stores the digital value representing the environmental temperature obtained by A / D converting the sensed environmental temperature in the internal memory, and obtains it. A digital signal (hereinafter referred to as temperature data) representing the present environmental temperature and the previous environmental temperature stored in the internal memory is sent to the CPU 11. The density adjustment key 14 also generates a digital signal representing a density adjustment value corresponding to the key operated by the operator and sends it to the CPU 11.

The ROM 13 stores an adjustment table in which the amount of change in driving voltage and the amount of change in environmental temperature are associated with the density adjustment value.

The CPU 11 calculates the drive voltage change value and the environmental temperature change value based on the voltage data from the voltage detection circuit 16 and the temperature data from the temperature detection circuit 17. Then, based on the calculated drive voltage change value and the environmental temperature change value, the adjustment table stored in the ROM 13 is drawn to obtain the corresponding density adjustment value. After that, the current density set value stored in the internal memory of the LCD drive circuit 12 is read out, and the obtained density set value or the density input from the density adjustment key 14 is added to the read current density set value. A new density set value is calculated by adding the set values. Then, the current density set value stored in the internal memory of the LCD drive circuit 12 is updated with the calculated new density set value.

After that, the LCD drive circuit 12 drives the LCD 11 by the drive voltage signal based on the updated density setting value, and the image is displayed on the pixel matrix by the adjusted liquid crystal display density.

That is, in this embodiment, the voltage detecting circuit 16 constitutes the voltage detecting section, the temperature detecting circuit 17 constitutes the temperature detecting section, and the ROM 1
3, the adjustment table storage unit is configured, and the CPU 15 configures the liquid crystal display density adjustment unit.

FIG. 2 is a flow chart of the density adjustment processing operation executed under the control of the CPU 15. The density adjustment processing operation will be described below with reference to FIG.

At step S1, the power is turned on. In step S2, the LCD drive circuit 12 generates a drive voltage signal composed of a four-value drive voltage based on the current density setting value stored in the internal memory and supplies it to the LCD 11. After that, "0" is input to the built-in flag and the flag is reset. In step S3, the drive voltage from the LCD drive circuit 12 is detected by the voltage detection circuit 16 and stored in the internal memory, and the voltage data is output.

In step S4, it is determined based on the voltage data from the voltage detection circuit 16 whether the current drive voltage value is different from the previous drive voltage value. As a result, if they are different, "1" is stored in the flag and the process proceeds to step S5. On the other hand, if not, step S5 is skipped. In step S5, the difference between the current drive voltage value and the previous drive voltage value is calculated based on the voltage data.

In step S6, the temperature sensing circuit 17 senses the ambient temperature and stores it in the internal memory, and at the same time, the temperature data is output. Step S7
Then, based on the temperature data from the temperature sensing circuit 17, it is determined whether the current environmental temperature value is different from the previous environmental temperature value. As a result, if they are different, the flag is "1".
Is stored and the process proceeds to step S8. On the other hand, if not, step S8 is skipped. In step S8, the difference between the current environmental temperature value and the previous environmental temperature value is calculated based on the temperature data.

In step S9, the content of the flag is "1".
Is determined. As a result, if the value is "1", the driving voltage or the environmental temperature has changed.
If not, go to step S11. In step S10, a corresponding density adjustment value is obtained based on the driving voltage change value calculated in step S5 or the environmental temperature change value calculated in step S8.

In step S11, it is determined whether or not the density adjustment key 14 is operated to directly specify the density adjustment value by the operator. If it is designated as a result, the process proceeds to step S12, and if not designated, step S14.
Proceed to. In step S12, the density adjustment value directly specified by the density adjustment key 14 is fetched. Step S13
Then, a new density calculated based on the current density setting value stored in the internal memory of the LCD driving circuit 12 and the density adjustment value obtained in step S10 or the density adjustment value fetched in step S12. The current density adjustment value stored in the internal memory of the LCD drive circuit 12 is updated by the set value. In step S14, it is determined whether or not to continue the density adjustment processing. As a result, if it is determined to continue, the process returns to step S3 to start detection of the next drive voltage. On the other hand, if it is determined not to continue, the density adjustment processing operation ends.

Next, referring to FIGS. 1 and 2, the above-mentioned density adjustment processing operation will be further described with a specific example. First,
When the power is turned on, the current density set value "7C" stored in the internal memory of the LCD drive circuit 12 is read out, and a four-valued drive voltage based on the current density set value "7C" is supplied to the LCD 11. Supplied. Further, the drive voltage is detected by the voltage detection circuit 16 and the digital value "13" obtained by A / D conversion is stored in the internal memory.
At that time, in the other area of the internal memory of the voltage detection circuit 16, the digital drive voltage value “1” detected previously is “1”.
4 "has already been stored. CPU 15
Captures voltage data consisting of the current drive voltage value "13" and the previous drive voltage value "14". Since the two drive voltage values are different, the flag is set to "1" to calculate the difference "01" between the two drive voltage values. Step S1 to Step S5 Next, the ambient temperature is sensed by the temperature sensing circuit 17,
The digital value "14" obtained by A / D conversion is stored in the internal memory. Then, the CPU 15 takes in temperature data including the current environment temperature value "14" and the previous environment temperature value "18". Since the two environmental temperature values are different, the flag is set to "1" (the flag is already set to "1"), and the difference "04" between the two environmental temperature values is calculated. Steps S6 to S8

Next, since the flag is set to "1", the adjustment table of the ROM 13 is drawn based on the difference (driving voltage change value) "01" between the current driving voltage value and the previous driving voltage value. As a result, the density adjustment value “01” is obtained. Similarly, the density adjustment value "02" is obtained based on the difference (environmental temperature change value) "04" between the current environmental temperature value and the previous environmental temperature value. Then, the current density set value "7C" is read from the internal memory of the LCD drive circuit 12, and both current density set values "01" are added to the current density set value "7C".
And "02" are added to obtain a new density set value "7F",
The contents of the internal memory of the LCD drive circuit 12 are updated. At that time, the pre-driving voltage value stored in the internal memory of the voltage detection circuit 16 and the pre-environment temperature value stored in the internal memory of the temperature detection circuit 17 are also updated. Steps S9 to S13

After that, the above operation is repeated and L
Until the contents of the internal memory of the CD drive circuit 12 are updated, an image is displayed on the pixel matrix of the LCD 11 by the four-valued drive voltage based on the updated density setting value “7F”.

As described above, in this embodiment, the voltage detection circuit 16 and the temperature detection circuit 17 are provided, and R
The OM 13 stores an adjustment table in which the amount of change in driving voltage, the amount of change in environmental temperature, and the density adjustment value are associated with each other. Then, the CPU 15 obtains the density adjustment value from the adjustment table based on the change value of the drive voltage detected by the voltage detection circuit 16 and the change value of the environmental temperature detected by the temperature detection circuit 17. Then, a new density set value is obtained from the current density set value stored in the internal memory of the LCD drive circuit 12 and the obtained density set value, and the current density set value of the LCD drive circuit 12 is updated. ing.

Therefore, when the drive voltage of the LCD 11 changes or the environmental temperature changes in accordance with the change of the power supply voltage, the drive voltage of the LCD 11 is immediately changed according to the change amount and is always constant. Images can be displayed with the liquid crystal display density of. Therefore, the operator can be relieved from the troublesomeness of extra liquid crystal display density adjustment.

The algorithm of the density adjustment processing operation according to the present invention is not limited to the flowchart shown in FIG. In this embodiment, in addition to the voltage detection circuit 16 and the temperature detection circuit 17, the concentration adjustment key 1
Since it also has 4, it is possible for the operator to directly adjust the liquid crystal display density.

[0036]

As is apparent from the above, the liquid crystal display density automatic adjusting device of the present invention detects the driving voltage from the liquid crystal display display driving unit by the voltage detecting unit and the ambient temperature by the temperature detecting unit. Then, the liquid crystal display density adjusting unit calculates the drive voltage change amount and the environmental temperature change amount based on the voltage information signal from the voltage detection unit and the temperature information signal from the temperature detection unit, and further calculates both of these change amounts. Based on the adjustment table stored in the adjustment table storage unit, the liquid crystal display density adjustment value is obtained, and the liquid crystal display density set value stored in the internal memory of the display drive unit is updated. The drive unit supplies the liquid crystal display with a drive voltage based on the liquid crystal display density set value that is optimally adjusted according to changes in the drive voltage and the ambient temperature. It is.

Therefore, according to the present invention, the liquid crystal display density is automatically adjusted according to the change of the power supply voltage and the change of the ambient temperature, and the liquid crystal display is always displayed with the optimum liquid crystal display density without the operator's hand. Images can be displayed on the display.

[Brief description of drawings]

FIG. 1 is a block diagram of an automatic adjustment device for liquid crystal display density according to the present invention.

FIG. 2 is a flow chart of a density adjustment processing operation executed under the control of the CPU in FIG.

FIG. 3 is a block diagram of a conventional liquid crystal display density adjusting device.

[Explanation of symbols]

11 ... LCD, 12 ... LCD drive circuit, 13 ... ROM, 14 ... Density adjustment key, 15 ... CPU, 16 ...
Voltage detection circuit, 17 ... Temperature detection circuit.

Claims (1)

[Claims] 1. A liquid crystal display drive unit for supplying a drive voltage based on a liquid crystal display density set value stored in an internal memory to a liquid crystal display, and detecting the drive voltage from the liquid crystal display drive unit to drive the same. A voltage detection unit that outputs a voltage information signal that represents the voltage, a temperature detection unit that senses the environmental temperature and outputs a temperature information signal that represents the sensed temperature, and a drive voltage change amount and an environmental temperature change amount and their change amount The adjustment table storage unit for storing an adjustment table in which the liquid crystal display density adjustment values are associated with each other, and the drive voltage change amount based on the voltage information signal from the voltage detection unit and the temperature information signal from the temperature detection unit. Then, the amount of change in the ambient temperature is calculated, the liquid crystal display density adjustment value is calculated using the above adjustment table based on the calculated both changes, and the calculated liquid crystal display density adjustment value is calculated. The liquid crystal display density adjusting apparatus comprising the liquid crystal display density adjusting section for updating a liquid crystal display density setting values stored in the internal memory of the display driving unit based on the value.